The invention relates to methods and apparatus for processing yarn. In another aspect the invention relates to a method and apparatus useful for regulating the temperature of a heating fluid used in a yarn crimping zone. In another aspect the invention relates to a method and apparatus useful for regulating a heating fluid used in a yarn heating zone.
It is frequently desirable to crimp a yarn and thereby produce a yarn having increased bulk and cover and improved hand.
In a number of yarn crimping operations, the yarn is subjected to heating prior to and/or during the actual crimping operation. It is not uncommon to use a heating fluid to heat the yarn and the processing equipment either directly or indirectly to a temperature at or above the melting point of the yarn. In order to minimize the time required to start up the operation, the yarn and equipment are often heated directly or indirectly by the heating fluid during the stringing up operation which can cause the yarn to melt, complicating the start up operation.
It is also desirable to heat a textured yarn prior to winding in order to produce a straightened textured yarn for easier handling and where the texture of the yarn will return subsequently applying heat to the yarn. Frequently the textured yarn is heated in a straightening zone immediately preceding the winder and during the doffing operation or stringing up of the processing line there is a tendency for the yarn to wrap the pull off rolls.
An object of the invention is to prevent yarn from melting in a yarn texturing zone during string up of the processing line. Another object of the invention is to prevent yarn from wrapping pull off rolls during string up of the processing line or doffing of the winder.
Other objects, aspects and advantages of the invention will be apparent to those skilled in the art after studying the specification, drawing and appended claims.